Administration of luteinizing hormone releasing hormone (LHRH) to estrogen-primed female rats produces a physiological facilitation of mating behavior which is mediated by specific CNS sites. The aim of the present grant proposal is to elucidate the mechanisms by which the LHRH signal in the CNS is processed and translated into a behavioral event. To accomplish this aim requires closer examination of the LHRH signal itself, the behavior produced by the LHRH signal, and the signal-induced fluctuations in neuronal activity associated with the initiation and maintenance of sexual behavior. In terms of the LHRH signal itself, the specific aim is to determine the amino acid sequence of the LHRH decapeptide that is sufficient for the induction of sexual receptivity. This will be accomplished by infusing shortened portions of the LHRH molecule into behaviorally active CNS sites and measuring lordotic behavior. The mating behavior produced by the LHRH signal will be analyzed in terms of receptive, proceptive, resistive, and motivational components. This latter component will be measured in a choice box paradigm which, in combination with the other more standard behavioral indices, will provide a quantitative, descriptive analysis of LHRH-induced mating behavior. Finally, the proposed project will examine how and where the LHRH signal is translated into biological events. The hypothesis that LHRH acts through an estrogenic mechanism will be tested by rendering inactive the sites at which estrogen is known to act and determining if LHRH is still capable of inducing mating behavior. By recording single unit activity at specific CNS sites in the freely-moving animal and assessing the effect of LHRH administration on this activity while simultaneously measuring the degree of sexual receptivity, the neuronal sites at which LHRH acts to induce behavior will be established. The results of the present proposal will provide information on how the brain orchestrates behavior in response to the LHRH signal. It is hoped that the results will furnish a key to understanding the more global question of how brain mechanisms subserve behavioral function.